1. Field of the Invention
The present invention relates generally to a waterproof film having heat-preservative function and its manufacture method, more specifically, it relates to a waterproof heat-preservative film made by mixing phase-change microcapsules with a waterproof material and the manufacture method thereof.
2. The Prior Arts
With the development of technology, the natural materials used in dresses for outdoor activities in early days are getting out-of-date and gradually replaced by advanced artificial materials, except some minor materials with excellent specific properties, such as eiderdown.
For application under severe outdoor conditions, the sports clothes must be heat-preservative, waterproof, and lightweight. A waterproof cloth usually comprises a waterproof layer coated on an inner layer of the cloth. The material that is occasionally used as the waterproof layer includes polyurethane (PU), polyethylene (PE), acrylic resin, and the like. On the other hand, for heat preservation, the material, which is usually double-layered to keep air inside, could be eiderdown, artificial fiber, and cotton.
A dress made of any of abovesaid materials can preserve heat to some extents. However, it is usually heavy and thick. Changing phase of a substance to absorb and release heat is recently employed in preservation of heat for cloth industry wherein a phase-change material (PCM) is mixed with textile for heat preservation.
A typical phase-change material is capable of absorbing and/or releasing a substantial amount of heat when its phase changes, for example, from a solid state into a liquid state or vice versa. Paraffin hydrocarbon is an example of the phase-change materials employed in absorbing heat at a desired or higher temperature for being fused.
When a phase-change material is heated, it absorbs heat and preserves thermal energy by means of physical phase change. If heating goes continuously, the phase-change material is gradually and melted and consequently becomes a liquid phase. Thus, in order to prevent loss of the phase-change material in liquid phase, a high-molecular stuff is commonly adopted for packing the phase-change material in micro-capsulated form for repeat use.
Nowadays, the technology of phase-change microcapsules has already been applied to textiles. For instance, U.S. Pat. No. 5,585,475 proposes to mix a phase-change material with polymers for blending fibers and preparing clothing or bedding. In addition, U.S. Pat, Nos. 5,366,801 and 6,099,894 propose to blend a phase-change material with a polymer and to coat the mixture on surface of fiber or textile for preparation of heat-preservative clothes. U.S. Pat. No. 6,207,738 discloses a wet-style coating method for coating textile with a phase-change material in order to produce heat-preservative clothes.
However, the manufacture procedure by either blending or coating the phase-change material on surface of textile is rather complicated and expensive.
A primary objective of the present invention is to provide a waterproof, heat-preservative film by mixing phase-change microcapsules having heat-preservation function with a waterproof material and extruding or blowing the mixture to form the desired waterproof, heat-preservative film.
Another objective of the present invention is to provide a method for manufacturing a waterproof, heat-preservative film with reduced costs.
Yet, another objective of the present invention is to make waterproof, heat-preservative clothes based on the material made in accordance with the present invention.
In order to realize abovesaid objectives, a waterproof, heat-preservative film can be manufactured with the following steps:
(a) selecting a phase-change material and preparing microcapsules containing the phase-change material by mixing the phase-change material with a polymer;
(b) selecting a waterproof material and melting the waterproof material;
(c) uniformly mixing the micro-capsulated phase-change material in the melted waterproof material and solidifying the mixture that is in liquid stale by cooling it down to the room temperature and pulverizing the solid to form plastic particles containing phase-change microcapsules; and
(d) finally, using a film-blowing machine to form waterproof, heat-preservative plastic films with the plastic particles.
The plastic film so made can be cut and further processed for manufacturing waterproof heat-preservative clothes.
The waterproof material includes, but not limited to, thermoplastic polyurethane (TPU), polyethylene (PE), and acrylic resin. The phase-change material that is contained in the microcapsule is selected in accordance with ambient temperature and operation temperature and is subject to no specific constraints. The phase-change material includes, but not limited to, paraffinic hydrocarbons, straight-chain paraffins, or high-class alcohols. The phase-change materials could be microcapsulated and processed for further applications.
For more detailed information regarding advantages or features of the present invention, at least an example of preferred embodiment will be described below with reference to the annexed drawings.